In recent years, large-capacity rewritable optical disks have rapidly become popular through incorporation into DVD recorders, personal computers, and Blu-ray recorders. Moreover, in the case of optical disks mounted in mobile devices such as a lap-top computer, there have been strong demands for optical disk drives with lower profiles.
In order to lower the profile of an optical disk drive, it is important to lower the profile of an optical pickup device. It is anticipated that such profile-lowering can be achieved in the optical design or the mechanism design of an optical pickup device by revising the structures of primary components while retaining performance and functions of such primary components.
Examples of primary components of an optical pickup device include a semiconductor laser and a signal detecting light receiving element. Profile-lowering of an optical pickup device can be achieved by lowering the profiles of such semiconductor devices.
As an example, structural schematic diagrams of a conventional semiconductor device are shown in FIGS. 11A, 11B, and 11C. FIG. 11A is a perspective view of a semiconductor device; FIG. 11B is a perspective view of the semiconductor device before applying a cap; and FIG. 11C is a cross-sectional view showing an internal structure of the semiconductor device.
In FIGS. 11A, 11B, and 11C, a semiconductor device 1 includes: a semiconductor laser 2; a semiconductor laser submount 3; a package 4; a cap 5; a piece of glass 6 that transmits a laser light 10 outputted by the semiconductor laser 2; a pair of lead terminals 7; a wire 8 connecting both anode and cathode electrodes of the semiconductor laser 2 and the lead terminals 7; and a piece of low-melting glass 9 for fixing the lead terminals 7 to a penetrating hole provided on the package 4.
In a method of manufacturing the semiconductor device 1 shown in FIGS. 11A, 11B, and 11C, the package 4 is fixed in advance by the piece of low-melting glass 9 to the lead terminals 7 electrically connected to the semiconductor laser 2 and leading out of the package. The semiconductor laser 2 mounted on the submount 3 is then bonded to the package 4. Next, both the anode and cathode electrodes of the semiconductor laser 2 are connected by the wire 8 to the pair of lead terminals 7. Next, the piece of glass 6 is fixed to a window provided on a lateral face of the package by the piece of low-melting glass 9. Finally, the cap 5 is fixed and sealed onto an upper face of the package by an adhesive or by seam welding.
The profile of the semiconductor device 1 shown in FIGS. 11A, 11B, and 11C is lowered as a configuration that outputs a laser light 10 of the semiconductor laser 2 from a lateral face of the package 4, and is capable of responding to demands for a thickness 11 of the package 4 of 2.4 mm or greater. In addition, by using metal for the package 4 and the cap 5, and sealing the piece of glass 6 and the lead terminals 7 by the piece of low-melting glass 9 and the cap 5 by seam welding, hermetic sealing can also be achieved.
The profile of an optical pickup device 12 can also be lowered by using the semiconductor device 1.
FIG. 12 shows a schematic diagram exemplifying a conventional optical pickup device equipped with a conventional semiconductor device.
In FIG. 12, the semiconductor device 1 is mounted in a chassis 13 of the optical pickup device 12. The semiconductor device 1 and an optical disk 14 are optically linked via an optical component 15 that, in this case, is a collimated lens, an erecting mirror 16, and an objective lens 17. More specifically, a laser light 18 outputted from a semiconductor laser chip (not shown) of the semiconductor device 1 shown in FIG. 12 is collimated to a parallel light by the optical component 15, has its optical path bent by 90 degrees by the erecting mirror 16, and is focused on a pit recorded on the optical disk 14 by the objective lens 17. Having read a signal on the pit, the laser light 18 is reflected by the optical disk 14 and proceeds along the same route in the opposite direction. At this point, the laser light 18 is bifurcated by a diffraction optical component 19 disposed between the optical component 15 and the erecting mirror 16, collected by the optical component 15, and enters a light receiving element (not shown) to read the signal recorded on the optical disk 14.
In order to lower the profile of the optical pickup device 12, the thickness 11 of the semiconductor device 1 may be reduced. In other words, by reducing the thickness 11 of the semiconductor device 1, the profile of the optical disk drive can be lowered.